This device relates to the field of closures for buildings typically having hinged doors which require an entry-proof locking arrangement.
Many devices are available to frustrate the practice of inserting a thin flexible tool between the door and jamb member to slide the bolt back into the door, allowing the door to swing open. These burglar-proofing guards, once discovered by the wrongful entrant, often lead to more forcible entry of the door.
Persons without keys wanting to make unauthorized entry into locked buildings have been able to do so by thrusting themselves or other weighted objects against the door. This splits the wood jamb dislocating the retention of the lock bolt which normally passes from the door into the strike plate keeper, thereby allowing the door to be opened and entry to be gained.
In a typical installation of the door, the door is hinged at two or three locations on one vertical side of a door frame, and is kept closed or locked at the other vertical side of the door frame at only one location. At the single door-locking location there is a retractable lock bolt which normally extends from the edge surface of the door. The bolt can be pivotally or slidably mounted inside the door in a spring-loaded manner allowing it to deflect to one side, or retreat into the door, upon one's closing the door. During closing the bolt passes the strike plate until it is received in strike plate opening. The bolt can then be locked in a non-retractable position by a key or other locking means. Because the bolt is usually the strongest element of a lock, when in its extended position the bolt itself resists thrust forces against the door. What usually occurs during thrusts against the door is that the wooden jamb splits or fails, allowing entry.
The purpose of this invention is to provide a substantially stronger and more entry-proof locking area of a hinged door by reinforcing the lock bolt receiving area, while making ajustable the space between the lock bolt and its keeper edge in the stroke plate.
According to the present invention, a security strike plate assembly is mounted to the jamb of a door either before or after the installation of the jamb piece into the door opening. When mounted to the jamb piece before its installation in the door opening, some of the mounting screws therefor will become inaccessible, thereby rendering the security plate practically permanently affixed to the jamb piece, once the jamb piece is installed into the door frame.